1. Field of the Invention
The present invention relates to a liquid crystal display device and a manufacturing method thereof, and more particularly to a liquid crystal display device which can enhance the brightness of a screen and a manufacturing method thereof.
2. Description of the Related Art
As a display device of an information communication terminal such as a computer or a display device of a television receiver set, a liquid crystal display device has been popularly used. The liquid crystal display device is a device which controls the alignment of the liquid crystal composition sealed between two substrates to display an image by changing the degree of optical transmissivity of liquid crystal composition.
As a method of controlling the alignment of the liquid crystal composition, there have been known a TN (Twisted Nematic) method and an IPS (In Plane Switching) method. Further, as a type of the TN (Twisted Nematic) method, there has been known a VA (Vertical Alignment) method. In the TN method and the VA method, pixel electrodes are mounted on a thin film transistor substrate (hereinafter referred to as “TFT (Thin Film Transistor) substrate”), and counter electrodes are mounted on a color filter substrate which is provided on a side opposite to the TFT substrate by way of a liquid crystal layer. The alignment of the liquid crystal composition is controlled by controlling an electric field generated between the pixel electrodes and the counter electrodes. On the other hand, in the IPS method, both pixel electrodes and counter electrodes are mounted on a TFT substrate side, and the alignment of the liquid crystal composition is controlled by controlling an electric field generated between the pixel electrodes and the counter electrodes.
FIG. 13 shows a state of arrangement of drain signal lines 801, source electrodes 802 and pixel electrodes 803 on a conventional TFT substrate 800 which makes use of the IPS method. A video signal applied to the drain signal line 801 is applied to the pixel electrode 803 electrically connected to the source electrode 802 via a channel portion 805 of a transistor. Here, counter electrodes (not shown in the drawing) which are formed on the whole surface of a display region are provided between a layer on which the pixel electrodes 803 are formed and a layer on which the source electrodes 802 are formed. The liquid crystal composition sealed in a layer above the pixel electrodes 803 is controlled such that when a voltage is applied to three divided portions of the pixel electrode 803, an electric field is generated between the three divided portions of the pixel electrode 803 and the counter electrode so that liquid crystal composition is controlled. A region indicated by symbol BM in the drawing shows a region of a black matrix which blocks light. An image is displayed due to the radiation of light through opening portions other than the black matrix region.